746 APPENDIX. 



To adjust the focus of the object-glass, turn the 

 milled heads o for a quick movement, or the milled head 

 p for a slow one. 



The stage, D, is circular, and upon it fits a plate, T; 

 this again carries the object-holder, u, which is provided 

 with a ledge, v, and a light spring, w ; it is held on the 

 plate T by a spring underneath, so that it can be moved 

 about easily and smoothly by one or by both hands. The 

 small spring, w, is fastened to the object-holder by a 

 milled head, which will unscrew ; so that the position of 

 the spring may be altered to give more or less pressure 

 upon the edge of the object, or it may be removed alto- 

 gether, if necessary. 



When a stage with only a flat surface is required, the 

 object-holder, u, may be removed by unscrewing, from the 

 under side of the plate T, two small milled heads which 

 connect a circular spring with the object-holder; or, by 

 removing the plain stage altogether, an extra simple flat 

 plate may be substituted. 



Beneath the stage there is a cylindrical fitting for the 

 reception of a diaphragm, or for any additional apparatus 

 that may be required in that position. 



The mirror, B, besides swinging in a rotating semicircle, 

 will slide up or down the tube, H, or it will turn on either 

 side for oblique illumination. 



Their Educational and Student's Microscopes, and larger 

 instruments are well known, and therefore need no 

 particular mention. 



CROUCH'S CHEAP BINOCULAR MICROSCOPE. 



The instrument (fig. 359) manufactured by Mr. H. Crouch, 

 London Wall, possesses many important advantages as a 

 cheap microscope. First it combines perfect optical per- 

 formance with good workmanship in the construction of 

 the stand. It is well balanced, and stands firmly in any 

 position. The polariscope can be used (the analyser 

 being adapted to binocular) with the 2-inch. The 

 stage is of a new construction, giving universal move- 

 ments of 1 J inch in extent. The condenser is on a separate 



